主燃孔对旋流杯下游流场的影响

Effect of primary holes on the velocity profiles downstream of a swirl cup

关键词:  燃烧室  旋流杯  主燃孔+  喷雾  流动分布  激光测量

Key words:  Combustion chamber  Swirl cup  Primary hole~+  Spraying  Flow distribution  Laser diagnostics

摘要:

采用PDA(Phase Dopp ler Analyzer)测量系统对带双轴向旋流杯、主燃孔和冷却气流的模型燃烧室的主燃区流场(以下简称真实结构)进行了实验研究,测量了燃烧室内流场的特性,并与不带主燃孔和冷却气流的头部旋流杯(以下简称纯头部结构)的气流场进行了对比。发现真实结构燃烧室内的回流区不再是轴对称,主燃孔和二次气流的存在使回流区明显被压扁(最扁处的长轴约为短轴的1.6倍);真实结构的回流区长度明显缩短,其长度L与旋流杯出口直径D的比值(L/D)约为1.3,而纯头部结构的L/D约为2.5。

Abstract:

The characteristics of the flowfield in the primary zone of a model combustor,which is confined by the swirl cup with double axial swirlers and the flame tube with primary holes and cooling air films,was investigated experimentally by a Particle Dynamic Analyzer(PDA).By comparison with the previously reported data for the flowfield after a pure swirl cup,it is concluded that the flowfield,especially the recirculation zone,in the primary zone is no longer axisymmetrical.The presence of the primary hole air flows remarkably squeezes the recirculation zone,resulting in a elliptic-like cross section,with the long axis approximately 1.6 times longer than the shorter one.The length of the recirculation zone is as short as about 1.3D,which is distinctly shorter than 2.5D for a pure swirl cup,in which D is the exit diameter of the swirl cup.